Transcript Folie 1 - zcu.cz

IEC 62478
A Prospective Standard for
Acoustic and Electromagnetic
Partial Discharge Measurements
Michael Muhr
Univ.-Prof. Dipl.-Ing. Dr.techn. Dr.h.c.
Institute of High Voltage Engineering and System Management
University of Technology Graz
IEC 62478
Partial Discharge (PD) Measurement
Sensitive nondestructive method
as important diagnostic tool
for evaluation of the insulation condition
PD-defect
Location and Detection
Electrical
Non electrical methods
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IEC 62478
Partial Discharge Measurement
Macroscopic-Physical
Effects
HV
Detection Methods
Optical Effects
(Light)
Optical
Pressure Wave
(Sound)
Mechanical
Opto-acoustic
Discharge Effects
Dielectric Losses
High Frequency
Waves
Electrical
IEC 60270
Chemical Effects
Chemical
Heat
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Acoustic
HF/VHF/UHF
IEC 62478
PD-Detection Methods IEC 60270
• Conventional electrical measurement
- Integration at frequency domain
Narrow-band
Wide-band
- Integration at time domain
ZFilter
Test
object
Coupling
capacitor
HV
measure
PD
Pulse
G
PD-System
HV-Source
Quadripole
Measuring impedance
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IEC 62478
PD-Detection Methods
• Electrical measurements with high frequencies
- HF / VHF method – 3 MHz to 300 MHz
- UHF method – 300 MHz to 3 GHz
• Acoustic measurements – 10 kHz to 300 kHz
• Optical measurements – ultraviolet – visible – infrared range
• Chemical measurements
Acoustic
HV
- Chemical
- Optical
PD
Directional
microphone
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IEC 62478
Optical – PD-Measurement
Eye
Light produced
during the discharge
Low-light
enhancer
Optical sensor
Fiber-optic cable
Infrared camera
Coronascope
Optical detection and localisation
Outside accessible:
- Eye
- Low-light amplifier
- Coronascope
Outside not accessible:
- Fibre-optic cable
- Collimator
- Photodiodes
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IEC 62478
PD – Optical Detection
Peak
Rd
Lens
Optical fibre
Voltage supply
M
CC
LWL
W
ST
PR
optical
system
Signalconversion
VP
Medium oil
Observation area
Optical fibre with lens
Peak
IEC 270
Oscilloscope,
conventional
opt. fibre
PC
ADU
fluorescent
opt. fibre
Measuring circuit after IEC 60270
and optical measuring system
Plate
Fluorescent optical fibre
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IEC 62478
Optical – PD-Detection in GIS
Photomultiplier
340
SF6
ADU
Oscilloscope
Test arrangement for optical PD-measurement
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560
670
780 nm
Emission spectrum of
corona discharges in SF6
I/U
Conv.
PD Detector
450
IEC 62478
Chemical – PD-Measurement
Arc
Partial discharge
Higher temperatures
SF6
decomposition
Sensors and analyser
- H2 Sensor
- DGA (Gas in oil analysis)
- Ozone analysis
- Gas Analysis
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fluoric compounds
(Fluoride)
Sulfur-compounds
(Sulfate, Sulfide)
Sulfur- fluoriccompounds
IEC 62478
Chemical – PD-Measurement
Fehlerart
C2 H 2
C2 H 4
CH 4
H2
C2 H 4
C2 H 6
PD
D1
D2
T1
T2
T3
>1
0,6 – 2,5
<0,1
<0,2
<0,1
0,1 – 0,5
0,1 – 1
>1
>1
>1
<0,2
>1
>2
<1
1–4
>4
IEC DGA Gas ratio values
• PD partial discharges
• D1 discharges with low energy
• D2 discharges with high energy
• T1 temperatures T < 300° C
• T2 temperatures 300° C < T < 700° C
• T3 temperatures T > 700° C
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IEC 62478
HF / VHF – PD-Measurement
HF / VHF – Partial Discharge Detection
• Frequency range 3 MHz to 300 MHz
- HF
3 – 30 MHz
- VHF 30 – 300 MHz
• Measuring systems
- Narrow-band, band width < 2 MHz
- Wide-band, band width
> 50 MHz
• Sensors
- Capacitive, inductive, electromagnetic
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IEC 62478
HF / VHF – PD-Measurement
Rogowski coil
Rogowski coil
PD Analyser
Measuring for HF – PD-detection on machines, VHF – PD-coupler,
Split ring Rogowski coil
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IEC 62478
HF / VHF – PD-Measurement
1
2
direct. coupling
A B
impulse
source / - No.
joint /1
left cable / 2
right cable / 3
direct. coupling
C D
signal at coupling output
A
B
C
D
–
X
X
–
X
–
X
–
–
X
–
X
Principle of the coupler sensor
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3
IEC 62478
HF / VHF – PD-Signal Damping
Damping effects:
- Geometric proportions
- Discontinuities
- Impulse form
- Refraction
- Reflection
- Frequency
- Material
B
A
LDP-5
C-Sensor
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IEC 62478
UHF – PD-Measurement
UHF – Partial Discharge Detection
• Transient electromagnetic waves
• Frequency range 300 MHz to 3 GHz
• Narrow band (~ 5 MHz)
• Wide band (~ 2 GHz)
• Propagation : - TM Wave (Transversal magnetic wave)
- TE Wave (Transversal electric wave)
- TEM Wave
• Not coupled to the conductor
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IEC 62478
UHF – PD-Measurement
Narrow band
Wide band
PRPD
pattern
Spectrum
analyser
amplifiers
low-pass
filter
Peak detector
UHF – PD-measurement
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PD measuring
instrument
IEC 62478
UHF – PD-Sensors
Detector
Dectector
Conductor
Conductor
Cage
Cage
- Mobile
UHF-window
sensor
- Conventional
UHF-sensors
Disc sensor
Cone sensor
Field grading electrodes
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IEC 62478
Sensitivity Verification
UHF
measurement
C1
Signal 1
C2
Defect
Impulses of
variable
amplitude
PG
UHF
measurement
C1
Signal 2
C2
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IEC 62478
UHF – PD-Fault Location
L1
L2
1
Amplitude
Defect
2
Sensor 2
Sensor 1
Measuring
instrument
Zeit
Pre amplifier
Time delay
Schematic arrangement
1 ... Sensor 1
2 ... Sensor 2
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IEC 62478
UHF – PD-Signal Damping, Sensitivity
Damping effects:
- Frequency
- Geometries
- Conductor material
- Mode type
- Reflection and refraction
Sensivity:
- Facility configuration
- Failure location
- Location of the sensor
- Measurement equipment
Sensitivity of developed UHF-sensors
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IEC 62478
Acoustic – PD-Measurement
Acoustic Partial Discharge Detection
- Acoustic signal as a result of the pressure wave produced by PD
- Frequency spectrum 10 Hz up to 300 kHz
SF6
Box
AE Sensor
Air
Principle schematic to the acoustic PD-detection
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IEC 62478
Acoustic – PD-Sensors
- Piezo-electric (sound emission)
- Structure-born sound-resonance
- Opto-acoustic-sensor
HV
HV
Sensor
Signal
PD
- Condenser microphones
- Accelerometer
PD
Time delay
Directional
microphone
Time
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IEC 62478
Acoustic – PD-Measurement
PD-Detector
AE Sensor
amplifier
Filter
A/D Converter
Acoustic – PD-detection system
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Oscilloscope
IEC 62478
Acoustic – PD-Measurement
Damping effects:
- Equipment dispersion
- Construction
- Insulation structures
- Gas pressure
- Encapsulation material
- Absorption during a
medium to another
- Geometrical spreading
of the wave
Acoustic fingerprint of a overhead line conductor
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IEC 62478
Opto-Acoustic – PD-Measurement
Reference optical fibre coil
Laser
Beam
Splitter
Beam
Splitter
Detector
Oil tank
Sensing optical
fibre coil
High
Voltage
PD-source
Experimental setup of the optical interferometric detection of PD
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IEC 62478
IEC TC42 WG 14
Content 1
- Scope
- Phenomena
• PD occurrence in discharging defects
• Frequency / time behaviour
• Specifies of HV-components
• Applicability for detection
- Normative References
- Definitions
- Sensors
• Types, parameters, positioning
- Location (time and frequency domain) vs measurement only
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IEC 62478
IEC TC42 WG 14
Content 2
- Transmission Aspects
A) UHF Aspects
• PD source, quantity E [V/m]
spectrum, filed mode, signal strength, magnitude, characteristic
impedance, velocity of medium, distance, activity
• Sensor-antenna, basic quantity [m]
type, bandwidth, position, receiving area, transfer impedance,
characteristics
• Reading quantity [V]
• Derived quantity
measuring equipment, bandwidth, center frequency, tuning
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IEC 62478
IEC TC42 WG 14
Content 3
B) HF / VHF Aspects
• PD source, quantity [V] or [A]
electric or magnetic signal, impedance, signal magnitude,
distance, activity
• Sensor – impedance [R, L, C]
type, bandwidth, position, dielectric attenuation, distortion,
polarity aspects
• Reading quantity [V, A]
• Derived quantity
measuring equipment, center frequency, tuning, bandwidth,
pulse resolution
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IEC 62478
IEC TC42 WG 14
Content 4
C) Acoustic Aspects
• Mechanical pressure, quantity [Pascal]
pressure waves, modes, acoustic impedance, delay, propagation
velocity, distance
• Sensor – impedance
piezo electric, composite material, optical, microphone,
directivity, position, coupling, bandwidth, linearity
• Reading quantity [V]
• Derived quantity
measuring equipment, pulse counter, pulse pattern
M. Muhr
IEC 62478
IEC TC42 WG 14
Content 5
- System Checks
Performance and sensitivity check
• UHF Aspects
performance check: functional check of the whole measuring
path including sensor and PD acquisition system
sensitivity check: emission of electromagnetic waves into test
objects, distance
• HF / VHF Aspects
performance check: sensor to sensor coupling in a specific
arrangement
sensitivity check: injection of field signal to test object, distance
• Acoustic Aspects
performance and sensitivity check: recommendation of acoustic
standards
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IEC 62478
IEC TC42 WG 14
Content 6
- pC Correlation
• HF / VHF / UHF – pulse generator injection to determine relation
between pC and measured quantities
• Acoustic: can not compared to pC without knowing the type of PD
source
- New quantities
• parameters linear with sensor output [mV]
• parameters quadratic with sensor output [mW]
• effective height [mm] – ratio between sensor output and incoming
electrical field
• Effective aperture [mm2] – ratio between maximum sensor output
power and power density of incoming electrical field
• sensor gain [dBi] – ratio between receiving power antenna and
receiving power of isotropic radiator
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IEC 62478
IEC TC42 WG 14
Content 7
EM – PD Source
Basic Quantity
E [Volt / meter]
Physical
Generic
Aspect
Sensor – Antenna
Basic Quantity e.g.
[meter]
Reading
Quantity
[Volt]
Low Standard Deviation
Mathematical
Term
Definition of Transfer
Characteristic
Quantity [m Watt]
PD [pC]
Quantity [Volt]
PD [pC]
High Standard Deviation
Low Standard Deviation
Definition of Transfer Characteristic
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System Check
IEC 62478
IEC TC42 WG 14
Content 8
Non Standardization
- Applicable sensor
- Test and measuring configurations
- Interpretation – task of the component panels
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IEC 62478
Thank You for Your Attention
M. Muhr